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Fukushima Blackout Hints at Plant’s Vulnerability

Members of the media toured the Fukushima Daiichi nuclear power plant in early March.Credit
Pool photo by Issei Kato

TOKYO — The stricken Fukushima Daiichi nuclear plant this week experienced its worst power failure since the disaster there in 2011, and though the plant’s operator said all electricity was restored by early Wednesday, the problem underlined its continuing vulnerability.

This week’s partial blackout, which started Monday, halted crucial cooling systems for as long as about 30 hours at four pools where used fuel rods are stored. The company that operates Fukushima Daiichi, the Tokyo Electric Power Company, said the plant had not been in danger because the fuel rods were never close to overheating, a state that could have led to a new, catastrophic release of radioactive materials.

The company said that temperatures in the fuel pools would have remained at safe levels for at least four days.

But the cutoff of the vital systems appeared to support fears by some experts and critics that the plant remains dangerous in part because some vital safety systems were makeshift fixes devised at the height of the nuclear crisis.

Tokyo Electric, also known as Tepco, acknowledged the concern. “Fukushima Daiichi still runs on makeshift equipment, and we are trying to switch to something more permanent and dependable,” a Tepco spokesman, Masayuki Ono, told reporters Tuesday as the company worked to restore the cooling systems.

The latest problems at the plant come as the government and the nuclear industry have been trying to convince jittery citizens that the country still needs its many nuclear plants. All of Japan’s plants were shuttered after the 2011 disaster as the government worked on stricter safety regulations. Two reactors were later restarted.

Prime Minister Shinzo Abe recently said that the plants would begin coming on line as they were deemed safe and began nudging Japan back to its reliance on nuclear power, which he said was a must for any economic recovery.

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The disaster two years ago also started with a blackout, brought on by a devastating earthquake and tsunami, which crippled the cooling systems for both the reactors and the spent fuel pools. Over the next several days, three reactors had triple meltdowns, leading to a wide release of radioactive materials that made the nuclear crisis the world’s second worst.

This week’s blackout did not affect the cooling systems for the three reactors, according to Tepco. Still, much of the continuing concern about the plant has focused on the fuel pools, which contain far more radioactive material than the reactors and were built with less shielding.

The four pools affected by the latest blackout contain more than 8,800 highly radioactive fuel rods, Tepco said, enough to cause a release much larger than the original accident, which forced the evacuation of some 160,000 residents in northeastern Japan. However, experts say that as the rods have aged with time, they are producing less heat, reducing the prospect of a catastrophic fire or melting.

With the company as the only source of information, it was impossible this week to independently assess the conditions at the plant, which sits in a contaminated zone that is closed to the public. On Tuesday, the company was criticized for waiting three hours before revealing the power failure to the public.

Tepco said a faulty switchboard might have been to blame in the latest power failure. Though the company has backup generators at the site, it appeared to have been unprepared for a switchboard failure.

Experts have been especially worried about the plant’s makeshift cooling systems, which could be knocked out by another large earthquake. Tepco said the temporary blackout also briefly cut off electricity to the command center at the plant.

Matthew L. Wald contributed reporting from Washington.

A version of this article appears in print on March 20, 2013, on Page A4 of the New York edition with the headline: Fukushima Blackout Hints at Plant’s Vulnerability. Order Reprints|Today's Paper|Subscribe